Although both Budai and Phra Sangkajai may be found in both Thai and Chinese temples, Phra Sangkajai is found more often in Thai temples, and Budai in Chinese temples. Two points to distinguish them from one another are:
Phra Sangkajai has a trace of hair on his head (looking similar to the Buddha's) while Budai is clearly bald.
Phra Sangkajai wears the robes in Theravadin Buddhist fashion with the robes folded across one shoulder, leaving the other uncovered. Budai wears the robes in Chinese style, covering both arms but leaving the front part of the upper body uncovered.